1. Field of the Invention
The present disclosure generally relates to vehicles having an internal combustion engine, a cranking motor, and a battery normally used to power the cranking motor. More specifically, the present disclosure relates to improvements to such systems that increase the reliability of engine starting.
2. Description of the Related Art
A problem presently exists with vehicles such as heavy-duty trucks. Drivers may on occasion run auxiliary loads excessively when the truck engine is not running. It is not unusual for heavy-duty trucks to include televisions and other appliances, and these appliances are often used when the truck is parked with the engine off. Excessive use of such appliances can drain the vehicle batteries to the extent that it is no longer possible to start the truck engine.
Various systems have been developed that use a capacitor to supplement the vehicle batteries such that the vehicle can be started. Often, however, the capacitor is not completely isolated, and can lose its charge over time, for example by leaking through one or more diodes. In other systems, wherein the capacitor is completely isolated when not in use, the capacitor is also isolated from the one or more switches or relays used to connect the capacitor to the cranking motor, such that the capacitor cannot be used to close the switch or relay to bring the capacitor on line.
Also, the operation of many existing systems is dependent on vehicle programming, and so such systems cannot be implemented as self-contained units connectable with the vehicle electrical system. For example, existing systems commonly use an oil-pressure sensor to detect when an engine is running, during which time the capacitor is connected to the system.
Additionally, capacitors in some existing systems cannot be used for cranking when the battery is completely discharged by auxiliary loads when the engine is not running.